AA 1997 then AA 3239 at O'Hare
St Louis → Chicago → Pittsburgh
Timetable, Chicago time
09:00AA 1997 from St Louis at the gate
12:29AA 3239 to Pittsburgh leaves the gate
3 h 29 apart on the timetable
The last days
AA 1997 and AA 3239 weren’t both flown 15 min to 12 h apart in the last 21 days.
Statistics from past flights, not live flight information. Always check times and your connection with your airline, and don’t base travel or booking decisions on these numbers.